Fabrication of hollow articles



June 25, 1963 T. F. PAULs 3,094,956

' FABRICATION oF HOLLOW ARTICLES:

Filed April 16, 1956 nel., y y* F'G-7- 73` 9 HG2. w

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3,@9455 Patented June 25, 1963 ice i 4. 3,094,956 u FABRICATION F HOLLOW ARTICLES j Theron F. Pauls, Godfrey, Ill., assigner to Olin Mathiesoll Chemical Corporation, East Alton,- Ill., a corporation or virginia Y Filed Apr. 16, 1956, Ser. No. 578,296 6 Claims. (Cl. 113-44) This invention relates to the fabrication of hollow articles and more specifically to the fabrication of hollowl articles which are smooth on one side.

vln the fabrication of hollow sheet metal panels by a well known process, two sheets of metal are arranged in stack-like fashion with a design of weld-inhibiting material applied to a portion of one of the adjacent faces of the sheets. The sheets are secured together to prevent relative slippage and are then welded together in their adjacent areas not separated by the weld-inhibiting ma'- t-erialin any suitable manner suchl as by hot rolling-.- As the sheets are being welded together by hot rolling they are elongated in the direction of rolling and therefore the design of weld-inhibiting material must be foreshortened in the intended direction of rolling when itis applied to the sheet. After the sheets are 'welded together they are usually softened as by annealing and the unjoined portion to which the weld-inhibiting material has been applied is outwardly expanded as by injecting therein a fluid pressure of suiiicient magnitude to permanently distend the sheets in the area adjacent to the weld-inhibiting design which may assume any desired configuration, for example, a design which wi-ll define, after expansion of the panel, a Huid conveying circuit of the type required in refrigerator heat exchanger panels. The aforementioned process is more fully described in U.S. Patent 2,690,002, issued September 28, 1954.

This invention oomprehends clamping a blank having an unjoined inner portion sandwiched between opposite `outer surfaces of the blank between a 'hard and a compressible pressure pad and then expanding the unjoined portion Iof the blank by injecting therein a iiuid pressure. The blank is dist/ended on the face adjacent the compressible pressure pad and is smooth on the side adjacent the hard pad.

As used.4 herein, the term smooth means a surface substantially devoid of depressions or protrusions in the overall general configuration of the surface.

This invention is directed primarily to the fabrication of metal panels, but in part the invention is equally applicable to panels fabricated from materials other than metal, such as various plastics, and to panels fabricated from dissimilar materials such as metal and a plastic joined .together with an unjoined portion between the sheets.

It is an object of this invention to fabricate a hollow panel in which one side is smooth and the other side is distended.

Another object tof this invention is to fabricate a panel having formed therein a hollow portion, such as fluid carrying conduits, the pane-l having a smooth surface and an opposite surface having protrusions conforming to the distentions of the hollow portion.

Another object of this invention is to provide an improved method of fabricating panels of the type disclosed in the aforementioned patent, U .S. 2,690,002, in which one of the outer surfaces has a high degree of smoothness.

Additional objects and advantages will be" apparent from the following description and drawings in which:

FIGURES l and 2 indicate schematically .a process for fabricating a blank from which a hollow smooth-sided panel is subsequently formed, and more specically:l

FIGURE 1 is a perspective View of a sheet of material 2 having applied to the lsurface thereof a pattern of weldinhibiting material;

FIGUR-E 2 is a perspective View of the sheet shown in FIGURE l `with a second sheet superimposed thereon in llaminar fashion and tacked thereto as by spot welding, with the 'pattern =of weld-inhibiting material sandwiched btwi the sheets and showing the sheets being welded together in a rolling mill to form a blank;

FIGURE 3 is a sectional schematic View of the resultant blank yof FIGURE 2 With the line 3 3 in FIG- URE l indicating the portion of the weld-inhibiting pattern shown in FIGURE 3, and showing the blank positioned between an embodiment of a pair of pressure pads;

FIGURE 4 is a sectional schematic view of theresultant blank of FIGURE 2 positioned between another embodiment of pressure pads, and with the same section through the blank as in FIGURE 3;

FIGURE 5 is a sectional schematic View similar to FIGURE 3 after the pressure pads have been clamped against the blank and the unjoined portion of the blank expanded;

FIGURE 6 is a schematic View of a control system for actuating the pressure pads and for expanding the maar; l Y

FIGURE 7 is a perspective view of the expanded blank 0f FIGURE 5; I

FIGURE 8 is a perspective View of the opposite side of the blank Shown in FIGUR-E 7. i

Referririgto the drawings, a sheet 1 such as aluminum yor copper has applied to a clean surface V3 thereof a serpentine design 5 and an inlet 6 of weld-inhibiting materia-l. A second sheet 7 is superimposed on the surface 3 of the first sheet 1. The two sheets are then tacked together as byl spot welding 9 to prevent relative slippage of the adjacent surfaces of the sheets during a subsequent welding operation. After the sheets have been tacked together they are welded together along their adjacent surfaces not separated by the weld-inhibiting material S. One well known method of `wel-dingthe sheets together is by hot rolling', in 4which the sheets are iirst heated' and then passed through mill rolls 114 between which they are reduced in thickness and elongated in the directioh of `rolling'. if desired, the resultant blank I13 having a'n u'njioined inner portion 15 may be softened in any appropriate manner as by annealing and4 thereafter the blank iay he cold rolled to provide a more even thickness andA again annealed. The inlet design of weldinhibi'tin'g mateial produces an unjoinedinlet into the unjirid serpentine design after welding together of the sheets'. j j

Referring to FIGURE 3, the resultant blank is positioned between a compressible pressure pad 17 and a hardr pressure pad 19. The compressible pressure pad is mountedona hard backing plate Z1 having coniining side walls 23 which engage the side wall of the compressible pad limiting outward displacement of the pad. The compressible pressure pad 17 and its backing plate 21' are positioned on a iixed jaw 25 of the press 27 and the hard pressure pad 1'9 is secured to a vertically moving jaw 29 of the press. The movable upper jaw 29 of the press is secured to a plunger 311 received in a cylinder 33 a Ifluid-tight sliding lit. The movable jaw yZ9 is` Imaintained in a raised position by a spring 35 chg-aging' a shoulder 37 on the lower end of the cylinder 33' and ashoulder 39 on the plunger 31. 'Ilhe cylinde'3'3 isixed with respect to the lower jaw 25 of the press iii ai1`y`approp.r'iateA manner 'as by arms 41. A fluid pressure conveying conduit 43 opens into ,the upper end of the cylinder33` fof injecting a duid into the cylinder 33 therehy forcing the plunger v 31 downward and the hard pressure pad 1159" against the compressible pressure pad 17'.

A i t The blank 13 is inserted between the pressure pads and a fluid pressure conveying nozzle 45 is inserted into the inlet in the blank. A fluid pressure is conveyed through the conduit 43 into the cylinder 33 clamping the hard upper pressure pad 19 against the lower compressible pressure pad I17 and .the horizontal sur-faces yof the walls 23 -of its backing plate 2l. The blank 13 is sandwiched between the hard pressure pad and the compressible pressure pad. The unjoined portion of the blank 13 is then expanded by injecting a uid pressure therein through the nozzle 45 Iand conduit 46 connected thereto.

-In order to assure ta smooth-sided hollow article 47 devoid of protrusions, the total compression of a compressible rubber pad 17 should be limited to between twenty and thirty percent for a 30 Shore-durometer rubber. I-f the percent of compression of the rubber is increased past this limit, the intended smooth side will tend to have formed therein distentions. The percentage of compression .is controlled by the height of the side walls 23 relative to the thickness of the rubber pad 17. Preferably the compressible pad should also be resilient such as a rubber pad, however, a pad which is not resilient will function properly to a degree but may not be reused.

FIGURE 4 shows another embodiment of the invention. In this embodiment, a hard pressure pad 49 is positioned on a lower iixed jaw 51 of a press 53 and a hydraulic chamber 55 having` a resilient diaphragm 57 adjacent the hard pressure pad 49 replaces the compressible pressure pad 17 in the embodiment shown in FIG- URE 3. The resilient diaphragm 57 is secured to the inner surface 59 of la peripheral side wall 60 of a chambered member 61 secured to an upper vertical movable jaw 63 of the press S3. A fluid pressure supply conduit 70 opens into the hydraulic chamber 55 for introducing 4therein a uid. The movable upper jaw 63 of the press is secured to a screw 67 rotatably mounted as at 69, on

the upper surface of the movable jaw. The screw 67 is threaded into a threaded socket 71 rigidly tixed to the lower jaw 51 of the press in any suitable manner such as by arms 73. Thus, by rotating the screw `67 lthe upper movable jaw 63 of the press may be raised or lowered. The blank 13 is inserted between the hard pressure pad 49 and 4the diaphragm 57 and the nozzle 45 is inserted into the inlet in .the blank. 'Ihe screw 67 is then rotated to clamp the side walls l60 ofthe hydraulic chamber against the hard pressure pad 49. Fluid pressure is -injected through -a conduit 70 into the hydraulic chamber and the blank 13 is then expanded by injecting a uid pressure into the unjoined portion thereof, through the nozzle 45 ,and a conduit 46 connected to the nozzle.

The outward distention 77 of the unjoined portion 15 of the blank 13 is controlled by ythe difference between the -force exerted within the unjoined porti-on of the blank and the force exerted by the compressible pressure pad 17 or the diaphragm 57 against the outer surface of the blank. In the embodiment shown in FIGURE 3, this control is obtained by increasing or decreasing the thickness of the compressible pad 17 relative to the height of the backing plate side Walls 23, since the hard pressure pad 19 engages the side walls. In the embodiment shown in FIGURE 4, the force exerted against the outer face of the blank 13 is controlled solely by the hydraulic pressure exerted by the fluid in the chamber 55 against the diaphragm 57.

Referring to FIGURE 6, with the press 53 shown in FIGURE 4 closed `and the blank 13 sandwiched between the hard pressure pad 49 and the diaphragm `57 and with al1 the valves closed, valves A and C are opened and a pressure of about 1,000 pounds per square inch is introduced from a pump into the hydraulic chamber 55 through conduit 70. Valve C -is then closed and valve B is opened, :injecting a pressure of about 1,000 pounds into the unjoined portion 15 of the blank and the pressure is then raised to between `1,500 and 2,000 pounds per square inch, depending on the thickness of the blank and the pressure required to fully distend the particular pattern of the unjoined portion of the blank. Valve A is then closed Iand valve C is opened, equalizing the force exerted within the unjoined portion of the blank `and on the opposite exterior faces of the panel 47. Valve D is then opened, simultaneously discharging the pressure within the distended portion of the hollow article 47 and within the hydraulic chamber 55. The pressures indicated above are intended merely to clarify the example, the pressure actually used will depend on the strength land thickness of the panel and the unjoined pattern design.

It is usually necessary for these pressures to be released simultaneously. If the pressure within the unjoined portion 75 lof the panel 47 is released first the pressure of the diaphragm 57 against the distended portion of the panel may cause the distention to collapse. Conversely, if the pressure Within the hydraulic chamber 55 is released frst the pressure within the distended portion 75 of the panel 47 will cause the panel to rupture. After the pressures have been released, the screw 67 is rotated to separate the hard and compressible pressure pads and the resul-tant hollow article 47 is removed from the press 53.

As shown in FIGURES 7 and 8, the hollow article 47 is distended on one side 77 and smooth on the opposite side 79 which was against the hard pressure pad 19 or 49'.

Referring to FIGURE 3, the process of expanding the blank is substantially the same as vthe method of FIG- URE 4 with the following exceptions: With all the valves shown in FIGURE 6 closed, valves C and A are opened forcing the hard pressure pad 19 `against the side walls 23 of the backing plate 21 of the compressi-ble pressure pad 17. It is only necessary that sufficient pressure be applied through valve C to firmly press the hard pad 19 against the side walls 23. Valve B is then opened, exerting .the same pressure within the unjoined portion 15 of the blank 13 as is exerted in the hydraulic chamber 33 and valve 1C is closed. The pressure from the pump is then increased sucient-ly to fully inflate the unjoined portion of the blank. The pressure required will vary depending `on the thickness and strength of the blank and the configuration of the unjoined portion thereof. Valve A is then closed, and valve D and valve C are opened concurrently, simultaneously releasing the pressure in the hydraulic chamber 33 and within the distended portion of the panel. If the unjoined portion of the blank is distended to too great an extent, the smooth side of the panel may tend to pull in. This eifect may be eliminated by reducing the expansion pressure exerted within the unjoined portion of the blank.

Although the invention has been described with reference to certain specific embodiments, materials and details, various modifications and changes will be apparent to Vone skilled in the art and the invention is therefore not to be limited to such embodiments, materials or details except as set forth in the appended claims.

I claim:

l. An apparatus for use in expanding a hollow article from a blank formed of a plurality of sheets with said blank having an unjoined interior portion defined within joined portions of said sheets and also provided with an inlet for fluid pressure to said unjoined portion with said unjoined portion being adapted to contain -a fluid under pressure, said apparatus comprising a rigid pad having a surface against which one side of said blank is placed in 'adjacent relationship, compressible clamping pressure means adjacent the other side of said blank for applying a uniform pressure on the other side of said blank with said compressible clamping pressure means being operatively connected to said pad and opposite said surface so that said compressible clamping pressure means holds said blank against said surface, engaging means operatively connected to said compressible clamping pressure means for engaging said compressible clamping pressure means with and against said other side of said blank so that said compressible clamping pressure means holds said one side of said Iblank substantially contiguousiy against said surface during expansion of each unjoined portion, uid injecting means adapted Ito be operatively connected to said inlet while said blank is held against said surface by said compressible clamping pressure means for injecting into said unjoined portion a -uid under pressure of sufficient magnitude to expand said unjoined portion while said one side is held against said surface, and pressure relieving means operatively connected to said compressible clamping pressure means and said fluid injecting means to concurrently relieve the forces of said compressible clamping pressure means and the pressure applied Within the said unjoined portion of said blank.

2. The apparatus of claim 1 wherein said compressible clamping pressure means is a resilient solid.

3. The apparatus of claim 2 wherein said resilient solid is rubber.

4. The apparatus of claim 1 wherein said compressible clamping pressure means comprises a hydraulic chamber.

5. The apparatus of claim 4 wherein said hydraulic chamber has a flexible diaphragm adjacent said blank.

6. An Iapparatus for expanding a blank formed of a plurality of sheets having an unjoined interior portion defined `and contained within joined portions of said sheets provided with an inlet for fluid pressure to said unjoined portion with said unjoined portion being adapted to contain a lluid under pressure, said apparatus comprisingV a pair of opposed pressure means operatively oonnected to each other for receiving .said blank thereirnbetween, one of said pressure means being rigid and noncompressible and the other of said pressure means being compressible, said lrigid means having Aa surface against which one side of said blank is placed in adjacent relationship, engaging means operatively connected to said compressible pressure means for engaging said compressible pressure means with the other side of said blank s-o that said compressible pressure means applys a uniform pressure to said other side to hold said one side of said blank substantially contiguously against said surface during expansion of said unjoined portion, iiuid injecting means adapted to be operatively connected to said inlet while said blank is held against said surface by said compressible pressure means for injecting into said unjoined portion for expansion thereof a uid under pressure of suicient magnitude to impress said other side of said blank opposite said unjoined portion into said compressible means, :and pressure releasing means operatively connected to said compressible pressure means and to said Huid injecting means to simultaneously relieve the force of said compressible pressure means and said fluid .pressure applied within the unjoined interior portion of said blank.

References Cited in the lile of this patent UNITED STATES PATENTS 1,625,914 Seibt Apr. 26, 1927 2,066,085 Whistler Dec. 29, 1936 2,317,869 Walton Apr. 27, 1943 2,479,702 Rood Aug. 23, 1949 2,519,661 Johnson Aug. 22, 1950 2,582,358 Schoellerman Jan. 15, 1952 2,662,273 Long Dec. 15, 1953 2,690,002 Grenell Sept. 28, 1954 2,728,317 Clevenger et al. Dec. 27, 1955 2,741,205 Paulton Apr. 10, 1956 2,749,867 Engel June 12, 1956 42,762,395 Lamb Sept. 11, 1956 2,771,850 Wheelon Nov. 27, 1956 2,857,659 Staples Oct. 28, 1958 2,857,660 Staples Oct. 28, 1958 2,866,429 Staples Nov. 19, 1958 3,003,228 Thomas Oct. 10, 1961 

6. AN APPARATUS FOR EXPANDING A BLANK FORMED OF A PLURALITY OF SHEETS HAVING AN UNJOINED INTERIOR PORTION DEFINED AND CONTAINED WITHIN JOINED PORTIONS OF SAID SHEETS PROVIDED WITH AN INLET FOR FLUID PRESSURE TO SAID UNJOINED PORTION WITH SAID UNJOINED PORTION BEING ADAPTED TO CONTAIN A FLUID UNDER PRESSURE, SAID APPARATUS COMPRISING A PAIR OF OPPOSED PRESSURE MEANS OPERATIVELY CONNECTED TO EACH OTHER FOR RECEIVING SAID BLANK THEREINBETWEEN, ONE OF SAID PRESSURE MEANS BEING RIGID AND NONCOMPRESSIBLE AND THE OTHER OF SAID PRESSURE MEANS BEING COMPRESSIBLE, SAID RIGID MEANS HAVING A SURFACE AGAINST WHICH ONE SIDE OF SAID BLANK IS PLACED IN ADJACENT RELATIONSHIP, ENGAGING MEANS OPERATIVELY CONNECTED TO SAID COMPRESSIBLE PRESSURE MEANS FOR ENGAGING SAID COMPRESSIBLE PRESSURE MEANS WITH THE OTHER SIDE OF SAID BLANK SO THAT SAID COMPRESSIBLE PRESSURE MEANS APPLYS A UNIFORM PRESSURE TO SAID OTHER SIDE TO HOLD SAID ONE SIDE OF SAID BLANK SUBSTANTIALLY CONTIGUOUSLY AGAINST SAID SURFACE DURING EXPANSION OF SAID UNJOINED PORTION, FLUID 